Nuttapong Attrapadung

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Attribute-based encryption (ABE), as introduced by Sahai and Waters, allows for fine-grained access control on encrypted data. In its key-policy flavor, the primitive enables senders to encrypt messages under a set of attributes and private keys are associated with access structures that specify which ciphertexts the key holder will be allowed to decrypt.(More)
In functional encryption (FE) schemes, ciphertexts and private keys are associated with attributes and decryption is possible whenever key and ciphertext attributes are suitably related. It is known that expressive realizations can be obtained from a simple FE flavor called inner product encryption (IPE), where decryption is allowed whenever ciphertext and(More)
Homomorphic signatures are primitives that allow for public computations on authenticated data. At TCC 2012, Ahn et al. defined a framework and security notions for such systems. For a predicate P , their notion of P-homomorphic signature makes it possible, given signatures on a message set M , to publicly derive a signature on any message m such that P (M,(More)
Dual system encryption techniques introduced by Waters in Crypto'09 are powerful approaches for constructing fully secure functional encryption (FE) for many predicates. However, there are still some FE for certain predicates to which dual system encryption techniques seem inapplicable, and hence their fully-secure realization remains an important problem.(More)
We show a generic conversion that converts an attribute based encryption (ABE) scheme for arbitrary predicate into an ABE scheme for its dual predicate. In particular, it can convert key-policy ABE (KP-ABE) into ciphertext-policy ABE (CP-ABE), and vice versa, for dually related predicates. It is generic in the sense that it can be applied to arbitrary(More)
In this paper, we propose new non-monotonic attribute-based encryption schemes with compact parameters. The first three schemes are key-policy attribute-based encryption (KP-ABE) and the fourth scheme is ciphertext-policy attribute-based encryption (CP-ABE) scheme. • Our first scheme has very compact ciphertexts. The ciphertext overhead only consists of two(More)
Homomorphic signatures are primitives that allow for public computations for a class of specified predicates over authenticated data. An enhanced privacy notion, called complete context-hiding security , was recently motivated by Attrapadung et al. (Asiacrypt'12). This notion ensures that a signature derived from any valid signatures is perfectly(More)